AuPd bimetallic nanoparticles supported on reduced graphene oxide nanosheets as catalysts for hydrogen generation from formic acid under ambient temperature

Abstract

Monometallic Au and Pd, and bimetallic Au_xPd_y (x/y mole ratio Au/Pd: 3 : 1, 1 : 1 and 1 : 3) catalysts supported on reduced graphene oxide (rGO) have been synthesised by the sol-immobilization method. The structural characteristics, surface chemistry and binding energies of all catalysts were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) connected with mapping energy dispersive (EDX) as well as Raman and X-ray photoelectron spectroscopy (XPS). The TEM observations revealed that Au, Pd and Au_xPd_y nanoparticles are uniformly distributed on the rGO nanosheet surface, and the average particle size is 3–7 nm, with several uneven agglomerated particles. The bimetallic Au_xPd_y/rGO catalyst exhibited a higher catalytic activity and selectivity than the monometallic Au/rGO and Pd/rGO catalysts in the generation of hydrogen from formic acid decomposition in water at 50 °C under analogous reaction conditions. The higher activity of the bimetallic catalyst is ascribed to the synergetic effect of Au–Pd nanostructures and the increased reaction sites evenly distributed on the rGO support. The reusability and the recovery test of the bimetallic Au_xPd_y/rGO catalyst for at least five times showed an insignificant loss of 7% of its initial activity.